There are many types of things that can be advantageously scheduled. This includes usage of manufacturing or other types of equipment, various tools, consumables, people, animals, buildings, rooms or other locations, and even intangibles such as procedures and access to data, software, sensors, etc. Indeed, as used herein, the term “resources” should be interpreted broadly to include anything that the use of which can be scheduled.
The importance of scheduling in a manufacturing environment can be obviated to some extent by increasing inventory, either finished goods inventory or work in process inventory. But the tradeoff is not always satisfactory. Inventory is expensive to produce and store, and suffers from possible degradation and obsolescence. In addition to the stock replenishment model, scheduling is important in make-to-order manufacturing environments, where shop orders are associated with a client order, and poor scheduling can result in extremely inefficient operation.
In service fields, trying to minimize the importance of scheduling by increasing inventory is either not even possible because the “product” being provided either cannot be stored, or is impractical because the “product” is unique to a particular circumstance. For example, medical examinations cannot be inventoried for future use, and must be done on specific patients, when the patients are available and the need arises. Analogous situations exist for plumbers, electricians and other service professionals, who only have so much time each day, and must maximize service time and minimize transit time.
Years ago, Toyota Production System (TPS) pioneered the concept of “lean manufacturing,” which was designed to reduce inventory costs of manufactured goods by producing the goods according to efficient production cycles. Among other things, TPS-type strategies design production cycles that minimize setup costs for making different parts on a given machine. Thus, if a machine is used to produce parts 1-6, it may be that the sum of all the setup times to produce each of the parts is smallest in the following cycle, 1=>3=>4=>6=>2=>5=>1 . . . . Once a cycle is determined to be the most cost-effective or a given piece of equipment, TPS-type systems continue to use that equipment according to that cycle, regardless of short term fluctuations in demand.
Although TPS systems have gained the most acceptance in manufacture of tangible goods, analogous strategies can be used in other contexts. For example in scheduling a conference room that is used for the same four meetings each day, with meetings 1 and 3 requiring tables and chairs, and meeting 2 and 4 requiring only chairs, a TPS type system might schedule the meetings in the order of 1=>3=>2=>4 rather than 1=>2=>3=>4 to minimize the setup time with respect to the tables.
Further discussion of TPS type scheduling can be found in U.S. Pat. No. 7,908,127 to Weignang et al. (2011), and U.S. Pat. No. 6,889,178 to Chacon (2005). Patents addressing sophisticate scheduling systems that do not use TPS include U.S. Pat. No. 8,185,422 to Yurekli (2012), US20070021998 to Laithwaite (publ. 2007), and US20090315735 to Bhavani (publ. 2009). These and all other extrinsic materials discussed herein are incorporated by reference in their entirety. Where a definition or use of a term in an incorporated reference is inconsistent or contrary to the definition of that term provided herein, the definition of that term provided herein applies and the definition of that term in the reference does not apply.
Interestingly, despite years of experience with TPS type scheduling, in many countries around the globe, there is still a need for systems and methods that can adapt such systems, in real time, to changes in short-term demand for parts scheduled to be produced according to a pre-established cycle.